p201 ct2: server side flag to not emit "point nb" event
When trying to reach maximum performance from ct2 card, the many small datagrams exchanged from server to client, corresponding to the "point nb" signal (= where we are in the acquisition) cause a lot of CPU consumption on both sides, impairing performance ; when CPU usage is 100% on server FIFO is filling up, and on the client side it can prevent greenlets to execute.